Unforgotten series 4 episode 4 recap: ITV episode ending explained

His disappearance in the 1990s can be linked back to four newly qualified coppers, now all middle-aged adults: Fiona Grayson, Elizabeth "Liz" Baildon, Dean Barton, and Ram Sidhu.

Read on for everything you need to know about the ending of Unforgotten episode four – and for all the questions we still need answers to later in the series.

Unforgotten episode 4 ending explained

*Warning: contains spoilers for Unforgotten episode four**

Unforgotten season four finally picked up the pace in the fourth episode, with new discoveries about victim Matthew Walsh's cause of death; secret meet-ups; and our first formal interview with one of the Unforgotten suspects.

The discovery of the rest of Walsh's remains at the end of episode three meant that Cassie and Sunny can finally work out exactly how he died.

Hidden in a lock-up, the near-mummified head and hands revealed that Walsh died after being impaled in the head with a sharp metal object, like a nail.

The working theory is that he was chased onto an allotment, where either he tripped and fell onto a nail or something similar – or that he tripped, was incapacitated, and someone deliberately stabbed him in the head where he lay.

We already knew that a man matching Ram Sidhu's description had been seen chasing Matthew Walsh the night he disappeared, but it's only now that things are starting to fall into place.

Firstly, we know that about three weeks before his disappearance, Walsh violently assaulted Ram inside a pub in a racially-motivated attack. However, Walsh wasn't charged with ABH (actual bodily harm), as senior police officers didn't want the attack to hit the news and for future BAME police applicants to be put off.

Secondly, Walsh's brother Clive finally resurfaced, and revealed that he'd been hiding nearby when he saw his brother being chased. He revealed that it wasn't just Ram who gave chase – all four suspects eventually got out of the car in pursuit of Walsh.

That means that any one of our four Unforgotten suspects - Fiona Grayson, Elizabeth "Liz" Baildon, Dean Barton, and Ram Sidhu - could have dealt the final death blow.

Cassie pulled serving police officer Ram in for questioning, but the interview went badly, as he denied remembering Walsh and accused her of racial profiling.

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What was Fiona's criminal conviction?

We previously learnt that police officer-turned-therapist Fiona Grayson had been hiding a past criminal conviction from her husband, potentially jeopardising their new business.

We also saw Fiona and Liz Baildon meet up secretly in episode four, when a frightened Fiona said: "They might find out what you did for me."

Later in episode four, we learnt that what that criminal conviction - and subsequent favour - was.

Cassie and Sunny learnt that Fiona had been involved in a speeding accident, killing a small boy. The police officers at the scene had smelt alcohol on her breath at the time, but she'd been so distressed that they hadn't been able to give her a breathalyser.

Instead, they took her down to the station and took a blood sample – which was then mysteriously lost, potentially saving her from a prison sentence.

And it turns out that that same police station was the one where Liz Bildon was working at the time.

Cassie and Sunny have two theories: either Liz and Fiona were once an item, and Liz stole the blood sample to protect her then-girlfriend; or, Fiona blackmailed Liz into stealing it, potentially by threatening to reveal something about the night Matthew Walsh disappeared.

What is the secret Eugenia blackmails Liz with?

We've long known that Cambridgeshire police officer Liz Baildon has an antagonistic relationship with her sharp-tongued, elderly mother, Eileen, who earlier in the series called to give a veiled threat when she heard about her daughter's job interview and potential promotion.

Eileen also told her carer and housekeeper, Eugenia, that there were secrets about Liz that would 'turn your hair grey'.

Now it seems that Eugenia is cashing in on that information, threatening to take it to the police and using it to blackmail Liz in order to get a (well-deserved) pay rise and cash bonus.

But what is the secret that Eileen told Eugenia? Could it be connected to the blood sample that went missing?

What is Dean's criminal past?

Fiona and Liz were the only suspects to meet face-to-face during the course of Unforgotten episode four.

Dean and Ram met up in a patch of deserted woodland, and not only did they discuss the Matthew Walsh case – it was also revealed that Ram had helped Dean in his recent, dodgy business deal.

Dean was previously seen picking up a white van in Calais, before driving it back to the UK in exchange for a wad of cash. But what was in that van, and how exactly did Ram help him? Did he pay off border control?

Unforgotten continues on Mondays on ITV. Want more show content? Read the latest Unforgotten episode 5 ending explainer. Check out our Drama hub for all the latest news. If you’re looking for something to watch tonight, check out our TV Guide.